Hydraulic crane



July 12, 1932.i l w FERR@A 1,866,801

HYDRAULI G GR NE ATTORN EY Patented July 12,* 1932 p UNITED STATESPATENT -ol-Flca WALTER FERRIS, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THEOILGEAB COMPANY, i

OF MILWAUKEE, WISCONSIN', A CORPORATION WISCONSIN HYDRAULIC CRANE Thisinvention relates to cranes and more particularly to hydraulic drivestherefor.

One object of the present invention is the provision of a hydraulicdrive for cranes so constructed and arranged as to return to the powersource a large portion of the energy ordinarily lost during lowering ofthe load.

.3D In the drawings Another object is the provision of a hydraulic drivefor cranes and the like in which two distinct hoisting speeds areavailable.

Another object is the provision of safety devices for drives of thischaracter which will operate automatically to check the fall of the loadin the event of failure in the power cir-y cuit or inthe hydraulicconnection.

Another object 'is the provision in a hydraulic circuit of the typeinvolving a reversible flow pump, of mechanism auto'- matically'operableto prevent movementof the motor when pump displacement is zero. Anotherobject is the provision in a crane of a system of reaving which willpermit the mounting of the hoisting motor on the bridge withoutinterfering with the hoisting functions or with the free travel of thecarriage along the bridge.

i Other objects and advantages will appear from the followingdescription of an illustrative embodiment of the present invention.

Figure 1 is a plan view of a crane embodying the novel featuresof thepresent linvention.

Fig. 2 is a view partlyA in section and partly in side elevation of thecrane of .Figure 1, taken substantially along the line 2-2 of Flgure 1.

` the usual brid Fig. 3 is a diagram of the hydraulic connections. i v lFig. 4, 5, and 6 are sectional views of three valves, respectively,shown in Figure 3.

The crane shown in Figures 1 and 2 includes -10 mounted for transversetravel along` t e fixed rails 11 in the usual manner, and supporting acarriage 12 mounted to travel alon the usual rails 13 extendinglengthwise o the bridge. The carriage is driven .by any appropriatemeans such as an electric motor 14 geared tothe drivin wheels of thecarriage4 in 'a manner weI known. A pair of sheaves 16 and 17 arerotatably supported upon ya shaft 18 fixed at its opposite ends inspaced brackets 15 fixed to f and depending from the central portion ofthe carriage. The sheaves 16 and 17 are arranged side by side invertical parallel planes extending lengthwise of the bridge.

A hoisting cable 19, anchored as at 2() at one end of the bridge, istrained over sheave 16, downwardly beneath a padlock sheave 21, upwardlyover the sheave 17 ,and then aroundl horizontal sheavesv 22 and 23rotatably fixed at the other end of the bridge. Thebther end of thecable is operatively connected with a hydraulic motor to be hereinafterdescribed. Sheave 22 and sheavesl and 17' are preferably so disposedthat the lengths of cable be- Y tween the anchorage,20 and sheave 16 andbetween the sheave 17 and sheave 22 lie substantially in one straightline, so that the loop '19 of the cable between sheaves 16 and 17 andsheave 21 remains substantially the same 'length during travel of thecarriage 12 along the bridge. The sheave 21 is equipped with a hook 24vor other appropriate load engagmg means.

The hoisting cable is actuated and controlled by a hydraulic motor whichis herein shown as a power cylinder 25 supported in fixed horizontalvposition in appropriate brackets 26 secured to the side of the bridge.-A piston 27'within the cylinder is provided with the usual piston rod 28which carries at its outer end a yoke 29, supporting a pair of sheaves30 and 31 freely rotatable on ashaft 32 lixed in the yoke 29. A sheave33 is mounted in a bracket 34 fixed to the opposite end of the cylinder25. The 'cable 19 extends from the sheave 23 over sheave 30 on. the'piston rod, then back over the sheave 33 on the cylinder, over theother sheave 31 on the piston rod,

and finallyto the bridge where itis firmly Y anchored as at 35. As thepisto'n 27 travels toward the left, sheaves 30 and 31 move aeeordingly'and the loop 19 of that portion of the cable between sheave 33 andSheavesjO- and 31 ,is extended. obviously shorbens the loopl 19 of thecableifand, the, hook 24 -is lifted. 'As the piston 27 travels towardthe nancy right loop 19" isA shortened and dloop 19'. lengthened tolower the hook 24.

he piston 27 is actuated by a hydraulic circuit, vwithout anaccumulator, which circuit is fed by an appropriate pump 36. The

pump shown is a reversible iow, variable displacement pump 'of the typefullydescribed in my applicatio2n,

December 21, v 19 3, which has matured into 1 Patent No; 1,558,002,issued October 20, 1925.A

It will suiiice here to say tliat this pump is driven at substantiallyconstant speed by any appropriate means such as an electric motor 37 andthat pum .displ-'a'cement isvaried from zero to fullelivery in eitherdirection by a control stern` 38. When the stem is in the neutralpositionl shown pump displacement. is zero. When the stem is shiftedlengthwise into the pump casing liquid is zo forced by the pump throu hpipe and returned to the pump throng pipe 39, the rate of flow beingdetermine by the extent of movement of the control stem from neutralposition. By shiftin the stem lengthwise in a direction away rom thecasing liquid lowsfrom the pump through pipe 39 and returns to the pumpthrough pipe 40. In

this instance the stem is operated by a llever 9, pivotally supported atits lower end upon l0 an appropriatebracket 8 fixed to the pump casing,and pivotally connected at its u per' endwith a rod-7 under the controlo the operator through appropriate linkage not shown. The stem ispivotally connected with 35 the lever 9, as at 6. v

Under some conditions of operation the pump 36 acts as a motor, underthe pressure of liquid returning thereto through the pipe 40, and when'so acting delivers a driving torque to the electric motor37. In orderto utilize this torque the electric motor 37 is of the regenerativetype, such as a constant speed, alternating current induction motor, ora constant spee'd shunt wound direct current motor, which, when drivenat a speed above normal, will act as a generator and feed back into thepower circuit.

- In the circuit da am illustrated in Figure- 3 it will be not that thepipe 40 is connected to the right end of cylinder 25 through valvemechanisms, hereinafter described, which remain open during normaloperation of' the crane., Pipe 40 is also connected f through a branchppe 41 with a valve 42 un' der the control o e operator. A pipe 43connects this valve with the left end of the cylinder. Pipe 39 is alsoconnected with this valve 42. Valve 42 is adjustable to connect eitheripe'39 or pipe 41 with the left end of der. Although this valve mayassume various'forms, that shown comprises a cylindrical housing 44enclosing a rotatable piston 45 under the control of the operatorthrough appropriate linkage including a rod. f i 47 an arml46 connectedwith the piston 45.

Serial No. 682,056, filed` LamieraI The piston is cut away so as to opencommunication between pipes 39 and 43 when in the full line positionshown and to open communication between pipes 43 and 41 when in thedotted line position shown.

Provision is preferably made for automatically blocking the escape oliquid from the right end of cylinderA 25 to thereby automatically lockthe piston against movement when pump displacement has been reduced tozero or in the event of failure in the power source. The hook 24 andvload supported thereby is thus held against falling when either of theabove conditions arise. For this purpose a valve of appropriate type isinterposed between the pipe 40 and the right end of the cylinder 25, andthis valve is placed under the control of a pilot valve which r'espondsto adjustment of the pump and to the condition of the power circuit. Avalve for this purpose is shown in Figures 1, 2, 3, and 5. This -valvecomprises a cylindrical housing 50 having two separate chambers 51 and52. l

Two spaced similar grooves 53 and -54 are formed in the wall of thechamber 51, groove 54 communicating with pipe 40 and' groove 54communicating with a pipe 40. A piston comprising two heads 57 and 58,connected by a reduced portion 59 is closely fitted for lengthwisereciprocation in the chamber 51. The arrangement is such that when thepiston isiin the upper position shown in Figure 5, piston head 57'isabove both grooves 53 and 54 and piston head 58 is below both grooves sothat pipe 40 is in-open communication with pipe 40. lThis is theposition of the piston during normal operation of the crane. When thepiston is in the lower position shown in Figure 3, piston head 57 coversgroove 53 and communication is eiectively closed between pipes 40 and40. The piston is controlled bya piston 60 connected thereto by a stem61 and closely fitted for reciprocation in the chamber 52. l Theopposite ends of chamber 52 are in open communication i with pipes 62and 63, respectively, controlled by a pilot valve of any appropriatetype.

The pilotvalve shown comprises a piston having two heads 64 and 65,connected by a reduced portion 66, and closely fitted or lengthwisereciprocation in the cylindrical bore 67 of ,a casing 68. The spacebetween the piston-heads is maintained flooded with liquid underpressure supplied from a convenient pressure source through pipe 69connected midway of the length of the bore 67. The oppositeends 'of thebore communicate at all times with a discharge pipe 71, through branchpipes 7 2 and 73. A groove 76 in the wall of the casing controlled bythe piston head 64 and a groove 77 iscontrolled bythe piston head 65.Pipe 62 is connected with groove 7 6 and pipe 63V with groove 77.- Thearrangement is such that when th'e piston is in the lower position ofFigure pipe 63 communicates with pressure pipe 69 and pipe 62 withbranch pipe 72 and discharge pipe 71, and when the plston-is in theupper position of Figure 4 pipe 62 communicates with pressure pipe 69and pipe 63 with branch pipe 73 and discharge pipe 71. The piston iscontrolled by a stem 78.

The pilot valve in this instance is placed under the joint control ofthe pump control mechanism and a solenoid which responds to thecondition of the electric power circuit for the motor 37. In themechanism shown this is accomplished by mounting a floating lever 79upon the stem 78 of the'valve. This lever is pivotally connectedintermediate its ends to the stem. Theright end lofthe lever isconnected with the armature of a solenoid 80. The solenoid is connectedthrough leads 81 and 82 with the opposite sides of the electric powercircuit for the motor 37. During the active condition of the powercircuit the solenoid is energized and holds the endV of the floatinglever 79 in elevated position against the action of the spring 83.Should the power circuit fail, however, the solenoid is deenergized andthe end of the lever falls under the action of the spring. A roller 84journaled within the left end of the floating lever 7 9 rides upon arotary cam 85 actuated bythe control rod 7 through a rack and pinion 85.With the rod 7, lever 9, and pump control stem 38 in the neutralposition of Figure 3, in which position pump displacement is zero, thecam roller is engaged in the depressed portion 86.of the cam 85 and theleft end of the lever 79 is depressed. Upon movement of the control rod.7, in either direction from this position, so as to cause the pump todeliver liquid in one direction or the other, the cam 85 is rotatedaccordingly and the cam roller 84 rises out of the depressed portion 86,lifting the left end of the iioating lever and the valve stem 78.

The arrangement is such that under normal conditions the right end ofthe floating lever is maintained in an elevated position by the solenoid80. With the control rod 7 in the -neutral position shown in Figure 3,pump displacement is zero, the c am 'roller 84 rests within thedepressed portlon 86 of the cam,

.the valve stem 78 is lowered, and the pilot valve is in such positionas to eiect communication between the pressure pipe 69 and' f pipe 63.Fluid pressure is thus applied above the other,ftl1'e cam 3,85 isactuated and the roller 84rises, out of the depressed portion,

thereof and lifts the left end of the floating lever, to thereby elevatethe valve stem 78 and lift the pilot valve into the position of Figure4. `Communication is thus established between the pressure pipe 69 andpipe 62, the piston 60 moves upwardly, and the piston valve in chamber51 assumes the upper position of Figure and communication is establishedbetween pipes 4() and 40. This condition is maintained until the controlrod 7 is returned to neutral position-or until yiailure in the electricpower circuit. Should the power circuit fail the solenoid would becomedeenergized and the right endof the floating lever would fall under thepressure of the spring, so as to lower the pilot valve and therebyadjust the valve 50, so as to block the hydraulic circuit. Provision isalso made for automatically shutting o the flow of liquidpfrom the rightend of the power cylinder in the event that breakage occurs in thepressure pipe 40, to thereby sustain the hook 24 and load againstfalling. This is .accomplished in this instance by inserting anothervalve in the hydraulic circuit between the pressure pipe and the rightend of the cylinder and by making this valve respond to an excessiverate of flow from the right end of the cylinder to cut off the flow. Avalve for this purpose is shown at 88 in Figures 1, 2, 3, and 6. Thevalve shown is similar to that shown in Figure 5 in that it comprises apiston having two heads 89 and 90 connected by a reduced portion 91 andreciprocating longitudinally in the cylindrical chamber 92 of the valvecasing. The space between the heads 89 and 90 is always in opencommunication with the right end of the power cylinder 25 through a port93, beneath the head 89, and through a Venturi tube 94 whichcommunicates at all times with the right end of the cylinder. A similargroove 95, communicating with pipe 40 is controlled by the head 90.'AThe piston is normally retained in the lower position shown in Figure 3by a compression spring 96 disposed in the upper endi of the chamber 92.In this posi-.

tion the head 90 is below the groove 95 and pipe 40 is in communicationwith the Ven-v turi tube and the right end of the power cylinder. Whenshifted into the upper position of Figure 6, however, the head 90 cov-'ers the groove 95 and communication .betweenpipe 40 and the Venturitube is blocked. The piston 1s raised by upward' movement of a p1sto1897to which it is connected through a stem The. piston 97 reciprocates in achamber 99 llt within the valve casing. A pipe 100 connects the upperend of chamber 99 with the restrictedpo'rtion of the Venturi tube and apipe 101 connects the lower end of chamber 99 with a wide portion of theVenturi tube.

The arrangement is such that during normal operationv of the crane thevelocity of liquid ilow through'the Venturi tube, to and from the rightend of the cylinder 25, is such that the difference in fluid pressure atthe restricted and wide portions of the Venturi tube is insufficient toraisethe iston 97 and valve against the pressure of e spring 96.

- Should the hydraulic circuit fail, however,

due for instance to a bursting ofthe p1 40,

so as to permit the high pressure liquid 1n the right end of thecylinder to escape through the venturi at high velocity, the diii'erencein pressure in the tpipes 100 and 101, due to this' hi h' velocity ow.'through the venturi, is

' s cient to lift the piston 97 against the pressure of thespring 96, sas to lift the valve into the position shown in Figure 6. The head 90then covers the groove 95 and thus eifectively blocks the further escapeof liquid from the cylinder. Itis of course understood that the rate oflow from the cylinder during normal lowerin is much less than uponrupture and not su cient to cause actuation of. the piston 97.

A brief crane will now be description of the operation of the given.Assume that the motor 37 is running, that the control rod 7 isin theneutral position shown so that pump displacement is zero, that thevalves 42:, 50, p

and 88 ,are in the positions shown in Figure 3, and that the ho'ok 24has been lowered to receive the load. To obtain a slow hoist the controlrod 7 is shifted toward the left so as to shift the cam 85 toward` theleft and the pump control stem 38 into the pum casing. The pilot-valveis thus lifted into t e upper position of Figure 4, the valve 50 israised so asto open communication between pipesv 40 and 40', and thepump delivers liquid through these pipes and through valve 88 andventuri 94 into the right end of the cylinder 25. The piston 27 is thusforced toward the left, expanding the loop 19. of the cable 19. andcontracting the loop 19' o f the cable to lift the load. During thismovementl of the piston 27 the fluid discharged from the left end of-cylinder isreturned to the 36 through pipe 43, valve 42, and pipe 39.

Forrapid hoisting the valve 42 is adjusted into the dotted line positionof Figure 3, so

as toopen ,communication between pipes 41 and 43. The-volume of liquidfrom the left end of the cylinder isthus-directed to the right endthereof and added to the volume of-liquid delivered by the 'pump tothereby obtain rapid travel ofthe piston 27 toward thel right. I Underthis condition .both ends of the cylinder are exposed to the deliveryside of the pump, so that the unit fluid pressure on both sides of thevpiston 27 is the` same. vIt will be noted however that' thearea of theleft face of the piston is reduced bythe area of the piston rod-28, sothat the pressure available to move the piston 1,see,ec1

trol rod 7 is shifted toward the right so as to adjust the Apump controlstem 38 toward the right, and to cause the cam roller 84 to rise out ofthe depressed portion 86. The valve is thus caused to again assume theupper osition of Figure 5, to reopen commumcatlon tween pipes 40 and40', and the pump discharges. into the pipe 39. During lowering, thevalve 42 isset into the full line position of Figure 3 so that fluiddelivered by the pump the cylinder 25 and the piston 27 is effectivelyvretained against movement.

To eeet lowering of the hook 24, the con' through pipe 39 passes throughpipe 43 into y the left end of the power cylinder. The iston 27 movestoward the right, the loop 19" of the hoistingcable contracts and theloop 19 expands, and the hook 24 lowers. Liquid dischar d from the rightend of the cylinder passes t rough the venturi 94, valve 88, pipe 40",valve 50 and pipe 40 back to the pum When lowerin' under load the pistonY is actuated prima y by the weight of the load on the hook 24 and bythe consequent tension in the loop 19 of the 'hoistingscabla Underl thiscondltrion the pump ten to speed up under the pressure of the liquid-foreed'from the cylinder 25 through pipe 40 thereto, and

the pump thus as a hydraulic motor tends to up the electric motor 37 soas to cause e same to act as a generator an return power to the electriccircuit.

Thus with a constant speedelectric motor of the' t hereinabove mentionedand a variable laement pump various' holstin speeds in a dition to thetwoabove describecf,

n as various lowering speeds, may be obtained by adjusting pump'displacement. During lowering un er loa the liquidl re turnin from thecylinder 25 to the pump 36,

Tthrong pipe 40, lsunder pressure proportional tothe load and, acting onthe pump, causes the pump to act as a motor, which reacting on the .eectric motor 37, tends toin- `crease the speed of the motor,therebycausmg the same to act as a generator and to' feed 'power backvinto the electric circuit.'y -No matter what lowering speeds have beenselected.- the above combination. recouverts the energy of the fallingloadinto wer.

Vianous changesmay be made 1n the eln-v bodlment o f the invention.hereinabove speclcally described without departing or sacrificing any ofthe advantages of the invention as defined in the appended clalms. Iclaim:

1. In a hydraulic crane, the combination of Va hoisting cable, a pistonand cylinder for operating said cable, said piston having faces ofunequal areas, a pump for delivering a driving liquid to said cylinderat a predetermined rate, and means adjustable to direct the liquid fromsaid pump to one end of said cylinder for slow hoisting or to direct theliquid from said pump to both ends of said cylinder for rapid hoisting.

2. In a hydraulic crane or the like, the

combination of a hydraulic motor, a variable displacement pump,-hydraulic connections between said pump and motor through which saidmotor is operated, a. valve in said connections, means for regulatingpump displacement, and means responsive to movement of said regulatingmeans for operating said valve to block the flow of liquid through saidconnections when pump displacement is zero.

3. In a hydraulic crane or the like, the combination of a hydraulicmotor, a variable displacement pump for operating said motor, means forregulating pump displacement, and means automatically operable to blockcommunication between said pump and motor when pump displacement iszero.

4. In a hydraulic crane or the like, the combination of a hydraulicmotor, a pump for operating said motor, an electric motor for operatingsaid pump and means responsive to a failure in said electric motor forblocking communication between said pump and hydraulic motor.

5. The combination of a hydraulic motor, a variable displacement pumpfor driving said motor, means for regulating pump displacement, meansfor driving said pump, a.

cut-olf valve between said pump and motor, and means operable to closesaid valve when pump displacement is z'ero or in the event of failure insaid pump driving means.

In witness whereof, I hereunto subscribe my name this 9th day ofFebruary, 1926.

WALTER FERRIS.

